The present disclosure relates to toner detection sensors and image forming apparatuses.
In image forming apparatuses typified by a digital multifunctional peripheral and the like, an image of a document is read by an image reading unit, and a photoreceptor included in an image forming unit is irradiated with light based on the read image, whereby an electrostatic latent image is formed on the photoreceptor. Thereafter, a developer such as charged toner is supplied onto the electrostatic latent image to form a visible image, which is transferred and fixed onto a sheet of paper fed. The sheet is then discharged to the outside of the apparatus.
Image forming apparatuses capable of forming full-color images include those which form a full-color image by overlaying images of respective colors of yellow, cyan, magenta, and black on one another. In this case, toner images of the respective colors are once transferred onto a transfer belt as an intermediate transfer body, and the resultant full-color image is transferred onto a sheet of paper. When forming a full-color image, it is necessary to perform corrections at certain timings so as to maintain high levels of color developing property and color reproducibility. In such corrections, the amount of toner on the transfer body is detected, and the developing bias value, the amount of exposure, the timing of exposure and so on are adjusted to achieve a proper amount of toner.
Techniques regarding the sensors which detect the amount of toner are conventionally known.
A typical gloss sensor is disclosed, in which a projector emits measurement light having a predetermined incident angle onto an object surface, and light reflected from the object surface is measured by a light receiver at the same angle as the incident angle, to measure the glossiness. In this gloss sensor, the projector emits light of a single wavelength. The projector is provided with a polarizer, through which the light is directed onto the object surface as polarized light in one direction. Light reflected from the object surface is transmitted through a polarization beam splitter, where the light is separated into a reflected light component having the polarized light in the same direction as the measurement light and a reflected light component in a different direction. The reflected light components are received by light-receiving means provided respectively for these components, and the outputs from the two light-receiving means are computed to thereby measure the glossiness.
A typical image forming apparatus is disclosed, which includes a recording medium conveyance belt rotatably stretched over a plurality of roller members. In this apparatus, at least one specular reflection detection type optical sensor and at least one specular reflection/diffuse reflection simultaneous detection type optical sensor are disposed to face an intermediate transfer body, and at least one specular reflection detection type optical sensor is disposed to face the recording medium conveyance belt or a second image carrier. In this apparatus, the at least one specular reflection detection type optical sensor disposed to face the recording medium conveyance belt or the second image carrier is used for black toner adhesion amount control, while the at least one specular reflection/diffuse reflection simultaneous detection type optical sensor disposed to face the intermediate transfer body is used for remaining color toner adhesion amount control. Further, in this apparatus, the at least one specular reflection/diffuse reflection simultaneous detection type optical sensor and the at least one specular reflection detection type optical sensor disposed to face the intermediate transfer body are used for color alignment control.